Purger for refrigeration system



Oct. 23, 1956 F. w. KNOWLES 2,767,559 PURGER FOR REFRIGERATION SYSTEMFiled Feb. 6, 1952 INVENTOR.

FRANK W. KNOW-LES BY'MM ATTORNEY United States Patent Ofifice 2,767,559Patented Oct. 23, 1956 2,767,559 PURGER- FOR REFRIGERATION SYSTEM FrankW. Knowles, Seattle, Wash. Application February 6, 1952, Serial No. 2701148; 1 Claim. (Cl. 62117.85D

The present invention relates to purger for refrigeration system, and inmore particular to a device for purging non-condensible gases from arefrigeration system, those gases which condense at much highertemperatures than the refrigerant gas used in the system. Suchnon-condensible gases are usually those constituent of air but maycontain dissociation products of the refrigerant gas as well as waterand oil vapors.

There have been many and various processes and apparatuses used inremoving, purging, these non-condensible gases from a refrigerationsystem. The present invention is an improvement on those purging deviceswhich employ a refrigerated surface within a container into which isintroduced a mixture of refrigerant vapor and non-condensible gases. Therefrigerated surface condenses a great amount of the refrigerant, andthe remaining mixture is allowed to escape to the atmosphere.

These prior systems have required much piping and equipment, and havenot always been efiicient in operation. Further, they have required muchof an operators time for their use.

Having in mind these defects of the prior art, it is an object of thepresent invention to devise and perform a purge process that has but fewsteps and lends itself to use in apparatus which is simple and elficientin operation.

A further object of the present invention is the processing ofrefrigerant vapor containing non-condensible gases, in a manner so thatthe heat of evaporation of such re frigerant will be used to effect theseparation of such vapor and gases.

A further object of the present invention is the construction of apurging device employing only two pipe connections to the refrigerationsystem.

Another object of the present invention is the construction of a purgedevice that may be regulated for operation so as to require a minimum ofan operators attention.

The above mentioned defects of the prior art and others are remedied,and these objects achieved in the device hereinafter described and shownin the accompanying drawings, in which:

The drawing shows an elevational sectional view partly in section of adevice embodying the present invention and parts of the refrigerationsystem with which it may be connected.

The principal part of the device shown in the drawing is an uprightcylindrical shell 1. This shell may vary in diameter and length with thecapacity of the system in which it is to be used and with the conditionsof the system that determine the rate at which the amount of unremovednon-condensible gases must be removed therefrom. Also, the amount ofunremoved non-condensible gases to be tolerated in the system may have abearing on the size. A shell three feet long and one-half foot indiameter, inside, will be ample for most systems between 100 and 250tons of refrigeration capacity. Heads 2, 3 are secured to and close theends of the shell. Passing thru the bottom end 3 is a receiverconnection pipe 4 that provides communication between the shell and thetop of a receiver 5 such as is usually found in a refrigeration system.

The, receiver is the place in a system that non-condensible gasesusually collect. If in a particular system they collect at anotherplace, then the purger may be connected to such place also. A shut-offvalve 6 may be placed in the receiver-connection pipe 4, but thisconnection should not: be trapped. The receiver connection pipe extends;into the purger shell 1 a distance of about five inches. Above andadjacent the upper end, the purger inlet 7, of the receiver connectionpipe 4 is placed a helical coil 8 or other heat exchanging means. Thiscoil extends upwardly to about the middle of the shell, and above thecoil is placed a baffle 9 that divides the shell into a lower part, thecondensing and liquid sections, and the upper part, the non-condensiblegas section 10. The liquid section 11 is that part of the inside of theshell which lies below the upper end of the receiver connection pipe,the shell inlet 7. The inlet 12 for the coil 8 opens into the liquidsection 11 of the shell below the purger inlet 7 and slightly above thebottom 3. Placed in the inlet section of the coil is an expansion orneedle valve 13. The outlet 14 for the coil 8 extends upwardly from thecoil, past the baffle 9, and thru the top head 2. Exterior of the shelland in the coil outlet is placed a coil shut-off valve 15. The coiloutlet 14 is connected to some part of the low pressure side of thesystem such as the suction line 16. Placed in the top nead 2 is anon-condensible gases outlet pipe 17 having therein a purge or needlevalve 18. This outlet communicates with the atmosphere or as otherwisedesired. The exterior or the shell should be insulated 19 for the bestperformance.

In the operation of this device, non-condensible gases and refrigerantvapor collect in the top of the receiver 5 and pass upward thru theconnection pipe 4, thru the purger inlet to the coil section, andthereinto contact with the coil 8. The refrigerant is condensed on thecoil and falls into the liquid section 11 from which it is drawn offthru the coil inlet, and expanded thru the expansion or needle valve 13.Expansion of the refrigerant into the coil 8 furnishes the refrigerationto condense the refrigerant in contact with the exterior of the coil.From the coil the expanded refrigerant passes to the low side of thesystem thru the coil outlet 14 and suction line 16. In the shell thecondensed refrigerant collects in the liquid section 11 until it reachesthe purge inlet 7 at which time the excess over that required for thecoil, returns to the receiver 5. The non-condensible gases pass upwardlythru the coil, past the baffle 9, thru the non-condensible gases section10, and out of the shell thru the purge outlet pipe 17 and valve 18,and, thus, out of the system. Proper design in the coil area andoperation in the passage of sufficient refrigerant thru the coil willcause the refrigerant to be separated from the non-condensible gases.The bafile 9 reduces turbulence and by-passing of the coil which mightresult in refrigerant vapor being carried to the outlet. Installation ofthe shell reduces reevaporation of the refrigerant and increases theefficiency of the device.

The purger requires only two connections to the refrigeration system andis otherwise simple in design and operation. After the expansion valve13 is properly adjusted and the purge valve 7 regulated, the device willoperate without attention. If the system has but negligible air leaksand refrigerant dissociation, the purger may be operated intermittently.In such a condition, the expansion valve 13 may be left open at alltimes and the purge valve 18 opened only occasionally.

Having thus described my process and a preferred device for use in theperformance of such process, I claim:

width, and top and bottom end closures for said shell,

an inlet pipe adapted to communicate with the receiver of such systemand said shell and to extend into the interior of said shell above saidbottom a distance substantially the width of said shell, the portion ofsaid shell below said communication opening forming a condensate trapand said pipe acting as a supply line for the flow of a mixture ofnon-condensible gases and refrigerant vapors from said receiver, andacting as an overflow for said trap for the flow to said receiver ofcondensate counter to such mixture, a heat exchange coil in said shellabove said inlet pipe, said coil having an inlet in communication withthe interior of said shell below the top of said inlet pipe,

an expansion valve in said heat exchange coil adjacent said inlet, saidcoil lying below the half height of said shell, a bafiie above andadjacent said coil, the outlet of said coil adapted to be incommunication with the low pressure side of said system, and a purgevalve and line connected to and in communication with said shell thruthe top of said shell.

References Cited in the file of this patent UNITED STATES PATENTS2,202,010 Kondolf May 28, 1940 2,327,081 Walters Aug. 17, 1943 2,577,598Zwickl Dec. 4, 1951

